Method of making planar geometry Schottky diode using oblique evaporation and normal incidence proton bombardment

Claim 1

A method of fabricating a Schottky diode comprising the steps of: providing a semi-insulating substrate of material selected from the group consisting of aluminum gallium arsenide, gallium arsenide and indium phosphide; growing sequentially an n+ doped layer of the material, an n doped layer of the material, and an undoped layer of the material consecutively on the substrate; depositing a polyimide on at least one region of the undoped layer; masking at least one region on the undoped layer to produce at least one masked and one unmasked region; etching away said unmasked region to produce a mesa with acute angled sides sloping inward from the top on the undoped layer so that the sides of the mesa define two recessed areas underneath the mesa; depositing a Schottky material at an angle on the exposed n doped layer so that the recessed area on one side of the mesa is not covered with Schottky material; depositing an ohmic material at an angle on the exposed n doped layer and on the Schottky material so that the recessed area on the other side of the mesa is not covered with ohmic material; bombarding the Schottky material and ohmic material with protons at normal incidence so that the recessed areas are untouched; and annealing the ohmic contact.

Claim 2

A method of fabricating a Schottky diode comprising the steps of: providing a semi-insulating substrate of material selected from the group consisting of aluminum gallium arsenide, gallium arsenide and indium phosphide; growing sequentially an n+ doped layer of the material, an n doped layer of the material, and an undoped layer of the material consecutively on the substrate; depositing a polyimide on at least one region of the undoped layer; masking at least one region on the undoped layer to produce at least one masked and one unmasked region; etching away said unmasked region to produce a mesa with acute angled sides sloping inward from the top on the undoped layer so that the sides of the mesa define two recessed areas underneath the mesa; depositing a Schottky material at an angle on the exposed n doped layer so that the recessed area on one side of the mesa is not covered with Schottky material; depositing an ohmic material at an angle on the exposed n doped layer and on the Schottky material so that the recessed area on the other side of the mesa is not covered with ohmic material; bombarding the Schottky material and ohmic material with protons at normal incidence so that the recessed areas are untouched; and annealing the ohmic contact.

Claim 8

A method of fabricating a Schottky diode comprising the steps of: growing an n + doped layer of gallium arsenide on a semi-insulating gallium arsenide substrate; growing an n doped layer of gallium arsenide on the n + doped layer; growing an undoped layer of gallium arsenide on the n doped layer; depositing a polyimide with a spinner on the undoped layer; curing the polyimide at approximately 150° C. for one half hour; aligning the substrate and n + layer, n layer, and undoped layer along the 011 orientation; providing a rectangular pattern on the undoped layer by use of a positive photoresist and a photoresist developer; etching a mesa on the undoped layer with a solution of one part sulfuric acid, one part hydrogen peroxide and two parts water to a depth so that all the undoped layer is removed exposing the n active layer; defining a pattern on each side of the mesa for contact metallization with positive photoresist; evaporating the Schottky material in vacuum on one side of the mesa with the n layer oriented approximately 60° with respect to the beam; rotating the n layer by approximately 60°; evaporating ohmic material in vacuum on the other side of the mesa; dissolving the photoresist with acetone; bombarding the n layer at normal incidence with approximately 150 KeV protons; and annealing the ohmic contact at approximately 425° for approximately two minutes.

Claim 9

A method of fabricating a Schottky diode comprising the steps of: growing an n + doped layer of gallium arsenide on a semi-insulating gallium arsenide substrate; growing an n doped layer of gallium arsenide on the n + doped layer; growing an undoped layer of gallium arsenide on the n doped layer; depositing a polyimide with a spinner on the undoped layer; curing the polyimide at approximately 150° C. for one half hour; aligning the substrate and n + layer, n layer, and undoped layer along the 011 orientation; providing a rectangular pattern on the undoped layer by use of a positive photoresist and a photoresist developer; etching a mesa on the undoped layer with a solution of one part sulfuric acid, one part hydrogen peroxide and two parts water to a depth so that all the undoped layer is removed exposing the n active layer; defining a pattern on each side of the mesa for contact metallization with positive photoresist; evaporating the Schottky material in vacuum on one side of the mesa with the n layer oriented approximately 60° with respect to the beam; rotating the n layer by approximately 60°; evaporating ohmic material in vacuum on the other side of the mesa; dissolving the photoresist with acetone; bombarding the n layer at normal incidence with approximately 150 KeV protons; and annealing the ohmic contact at approximately 425° for approximately two minutes.